MERKLE TREES

Also known as hash tree
Every leaf node is labeled with the hash of a data block
Every non-leaf node is labeled with the cryptographic hash of the labels of its child node
Merkle tree is a next concept that is widely used in the foundation for the blockchain concept it is called the Merkle tree.

So Merkle tree is a tree structure where the leaf nodes will contain the hash of the document and every individual node or intermediate node will contain the hash of the combination of the left child under a right child.

Above an example of a Merkle tree. The leaf node contains the hash of the content of this document.

the 1st leaf node contains the hash of D 1, 2nd leaf node contains the hash of D 2, 3rd leaf node contains the hash of D 3, and 4th leaf node contains the hash of D 4 and then this level 1, the intermediate node it contains the hash of these H 00; that means the hash value of D 1 plus the hash value of D 2 and the and their combined hash value than the root level.

so, this is an example of a binary Markle tree is root level, the root contains the combined hash of its left child and right child.

That means, if you are making any change in this document, that change will get reflected in the overall hash value.

If you want to secure a number of documents together; so in the bottom of the image assume that you want to secure all these 4 documents together, then you have the advantage that you can propagate 1 block (in top) root value.

So the root value if there is any change in any one of these 4 documents together, then that change will get reflected in the root value and that way ah that way you have the advantage that you can collectively secure a number of documents together by using this concept of Merkle tree.

USE OF MERKLE TREES

Bayer, herber and stornetta used merkle tree in 1992 for timestamping and verifying a digital document-improved the efficiently by combining timestamping of several documents into one block
Other uses of merkle tree
Peer to peer networks: data blocks received in undamaged and unaltered; other peers do not lie about a block
Bitcoin implementation-shared information are unaltered; no one can lie about a transaction
Now, this concept of Merkle tree was actually used in 1992 by extending the work where the earlier people in 1991 they have developed a chain kind of architecture to secure the time stamp values in a digital document and there here in 1992, Bayer Herber and Stornetta they have developed a mechanism where they have used a Merkle tree to secure the timestamp values for a number of documents for a set of documents.

Now, there can be other uses of Merkle tree-like in a peer to peer network whenever you are sharing a set of data blocks you want to ensure that the data blocks are received in an unmanaged and an unaltered way.

So, and other peers they are not lying about a block like they are sharing a block, but that block is not an updated block.

in that case, if you share the root hash of the Merkle tree, which is called the Merkle root; if you share the Merkle root the Merkle root ensures that none of the documents have been altered.

Another use full of the Merkle tree is the implementation of the Bitcoin, which is the most popular cryptocurrency which actually worked as the foundation of this concept of this blockchain.

So, in case of a bit can also you want to find out that the shared information which is there, that information is unaltered and no one is lying about some old transaction.

there also you can construct a Merkle tree of all the transactions together and if the same one is just denying one particular transaction, your Merkle root will change and by looking into the Merkle root you will able to validate that whether the set of transactions have been transmitted from one node to another node in an unaltered way or not.read more